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HYACC(1)                                                              HYACC(1)



NAME
       hyacc  -  LR(0)/LALR(1)/LR(1) parser generator. Similar utility as yacc
       and bison.

SYNOPSIS
       hyacc -?
       hyacc -h
       hyacc --help
       hyacc -V
       hyacc --version
       hyacc [-bcCdDghlmnoOPQRStvV]
             [-b file-name-prefix] [--file-prefix==file-name-prefix]
             [-c] [--no-compiler]
             [-C] [--keep-unit-production-with-action]
             [-d] [--defines]
             [-Di] (i = 0~15)
             [-g] [--graphviz]
             [-h] [--help]
             [-l] [--no-lines]
             [-m] [--man-page]
             [-o output-file-name] [--output-file==output-file-name]
             [-Oi] (i = 0~3)
             [-P] [--lane-tracing-pgm]
             [-Q] [--lane-tracing-ltt]
             [-R] [--lalr1]
             [-S] [--lr0]
             [-t] [--debug]
             [-v] [--verbose]
             [-V] [--version]


DESCRIPTION
       Hyacc is a program similar to yacc(1) and bison (LALR(1) parser genera-
       tors),  but  which accepts all LR(1) grammars and thus is more powerful
       than yacc(1) and bison.  It is backward compatible with input files  of
       yacc(1) and bison.  Hyacc also supports LALR(1) (based on lane-tracing)
       and LR(0).

       Input files should better follow the yacc convention of ending  in  .y,
       but don't have to. By default, the output file is y.tab.c. When you use
       -d you also get y.tab.h, and when you use -v  you  also  get  y.output,
       same  as  yacc.  The  user can use the -b or -o switches to specify the
       output file names.

       Hyacc supports both traditional single letter options and mnemonic long
       option  names.  Long  option  names are indicated with -- instead of -.
       When a long option takes an argument,  like  file-prefix,  connect  the
       option name and the argument with ==.


   OPTIONS
       Command line options are decribed below.

       Most options may be give in one of two forms: either a dash followed by
       a single letter, or two dashes followed by a long option name.


       -b fileprefix
       --file-prefix==fileprefix
              Specify a prefix to use for all hyacc output  file  names.   The
              names are chosen as if the input file were named fileprefix.c.


       -c
              Use  this  switch  to  not  generate  parser  files (y.tab.c and
              y.tab.h).  This is useful when the user only wants to use the -v
              and -D switches to parse the grammar and check the y.output file
              about the grammar's information.

              -c generally is used with -v, -D and -C.


       -C
              For the unit production removal optimization (when -O2 or -O3 is
              used), if a unit production rule has semantic action, when it is
              removed the semantic action won't be preserved,  so  the  output
              compiler will miss some code.

              To  solve this problem, by default HYACC adds a placeholder non-
              terminal to unit production rules with actions, so they won't be
              removed. E.g., from
              program : expression              {printf("answer = %d\n", $1);}
                      ;
              to
              program : expression $PlaceHolder {printf("answer = %d\n", $1);}
                      ;
              $PlaceHolder : /* empty */
                           ;

              If the -C switch is used, this default action will not be taken.
              This is used when the user wants to just parse the  grammar  and
              does  not care about generating a useful compiler. Specifically,
              -C is used together with switch -c.


       -d
       --define
              Write an extra output file containing macro definitions for  the
              token type names defined in the grammar.

              The file is named y.tab.h.

              This  output file is essential if you wish to put the definition
              of yylex in a separate source file, because yylex  needs  to  be
              able  to refer to token type codes and the variable yylaval.  In
              such case y.tab.h should be included into  the  file  containing
              yylex.


       -D
              Change  the  print  option  to  debug  file y.output. A user who
              checks the debug file should assume certain degree of  knowledge
              to the LR(1) compiler theory and optimization algorithms.

              If  the -v options is used, a debug file y.output will be gener-
              ated when hyacc parses the grammar file. Use of -D  switch  will
              automatically  turn  on the -v switch, and will allow to specify
              what kind of information to be included into y.output.

              By default, use -v will output the information about the states,
              plus  a  short statistics summary of the number of the grammar's
              terminals, nonterminals, grammar rules  and  states.   like  the
              y.output file of yacc.

              -D should be followed by a parameter from 0 ~ 14:

              -D0
              Include all the information available.

              -D1
              Include the grammar.

              -D2
              Include the parsing table.

              -D3
              Include  the  process  of  generating the parsing machine, basi-
              cally, the number of states and the current state in each cycle.

              -D4
              This  is  useful  only  if  at  the  time of compilation, in y.h
              USE_CONFIG_QUEUE_FOR_GET_CLOSURE is set to 0.   This  then  will
              include  the information of combining compatible configurations:
              the number of configurations before and after  the  combination.
              -D4 can be used together with -D3.

              -D5
              Include  the  information  of the multi-rooted tree(s) built for
              the optimization of removing unit productions.

              -D6
              Include the information in the  optimization  of  removing  unit
              productions. Specifically, the new states created and the origi-
              nal states from which the new states are combined from.

              -D7
              Include the information of the step 4  in  the  optimization  of
              removing  unit  productions. Specifically, this shows the states
              reachable from state 0.

              -D8
              Show the entire parsing table after removing  unit  productions,
              including those states that will be removed.

              -D9
              Show  a  list  of  configurations  and the theads of the strings
              after the scanning symbol.

              -D10
              Include information of the symbol hash table.

              -D11
              Include the information of shift/shift conflicts  if  any.  This
              happens  when  the  input grammar is not LR(1) or ambiguous, and
              the optimization of removing unit production is used. The occur-
              rence  of shift/shift conflicts means the optimization of remov-
              ing unit productions (-O2 and -O3) cannot  be  applied  to  this
              grammar.

              -D12
              NOT  to include the default information about states when the -v
              option is used. Use -D12 to show only the short statistics  sum-
              mary, and not the states list.

              -D13
              Include  the  statistics  of  configurations for each state, and
              also dump the state hash table.

              -D14
              Include the information  of  actual/pseudo  states.   An  actual
              state  number is the row number of that state in the parsing ta-
              ble. After the step of unit production removal, some states  are
              removed  but  their rows still remain in the parsing table, thus
              the state's pseudo  state  number  (counted  by  ignoring  those
              removed states/rows) will be different.

              -D15
              Shows  the  originator and transitor list of each configuration,
              as well as the parent state list of each state.  This  is  rele-
              vant when lane tracing is used.



       -g
       --graphviz
              Generate a graphviz input file for the parsing machine.



       -h
       --help Print a usage summary of hyacc.



       -l
       --nolines
              Don't  put  any  #line preprocessor commands in the parser file.
              Ordinarily hyacc puts them in the parser file so that the C com-
              piler and debuggers will associate errors with your source file,
              the grammar file. This options causes them to  associate  errors
              with  the parser file, treating it as an independent source file
              in its own right.


       -m
       --man-page
              Show man page. Same as "man hyacc". This is used  when  the  man
              page  file exists in the same directory as the hyacc executable.
              So if installation moves this man page file to another location,
              you must use "man hyacc".


       -o outfile
       --output-file==outfile
              Specify the name outfile for the parser file.

              The  other  output  files' names are constructed from outfile as
              described under the v and d switches.


       -O
              Specify the kind of optimization used to parse  the  yacc  input
              file.

              Basically,  three  optimizations are used: 1) Combine compatible
              states based on weak compatibility.  2) Remove unit productions.
              3) Remove repeated states after optimization 2).

              The -O switch should be followed by a parameter from 0 to 3:

              -O0
              No optimization is used.

              -O1
              Optimization 1) is used.

              -O2
              Optimizations 1) and 2) are used.

              -O3
              Optimizations 1), 2) and 3) are used.

              By default, when -O switch is not specified, the optimization 1)
              of combining compatible states is used.  So  "hyacc  file.y"  is
              equivalent to "hyacc file.y -O1" or "hyacc -O1 file.y".


       -P
       --lane-tracing-pgm
              Use  LR(1) based on the lane-tracing algorithm. The lane-tracing
              algorithm starts from a LR(0) parsing machine, uses lane-tracing
              to  obtain  contexts  to  resolve shift/reduce and reduce/reduce
              conflicts. If some reduce/reduce  conflicts  are  not  resolved,
              then  state-splitting  based  on the practical general method is
              used to resolve such conflicts.


       -Q
       --lane-tracing-ltt
              Use LR(1) based on the lane-tracing algorithm. The  lane-tracing
              algorithm starts from a LR(0) parsing machine, uses lane-tracing
              to obtain contexts to  resolve  shift/reduce  and  reduce/reduce
              conflicts.  If  some  reduce/reduce  conflicts are not resolved,
              then state-splitting based on a lane-tracing table  is  used  to
              resolve such conflicts.


       -R
       --lalr1
              Use LALR(1) based on lane-tracing.


       -S
       --lr0  Use LR(0).


       -t
       --debug
              In  the parser files, define the macro YYDEBUG to 1 if it is not
              already defined, so that the debugging facilities are  compiled.
              When the generated compiler parses an input yacc file, the parse
              process will be  recorded  in  an  output  file  y.parse,  which
              includes  all  the shift/reduce actions, associated state number
              and lookahead, as well as the content of state stack and  symbol
              stack.


       -v
       --verbose
              Write  an  extra  output file containing verbose descriptions of
              the parser states and what is done for each  type  of  lookahead
              token in that state.

              This  file also describes all the conflicts, both those resolved
              by operator precedence and the unresolved ones.

              The file's name is y.output.


       -V
       --version
              Print the version number of hyacc and exit.



   EXAMPLES
       Assume the input grammar file is arith.y.


       The user wants y.tab.c only:
              hyacc arith.y


       The user wants y.tab.c and y.tab.h:
              hyacc -d arith.y


       The user wants the generated compiler create  y.parse  when  parsing  a
       program:
              hyacc -dt arith.y
              or
              hyacc arith.y -d -t


       The user wants y.ta.b, y.tab.h, and create a y.output file when parsing
       the grammar:
              hyacc -dv arith.y


       The user wants, y.tab.c, y.tab.h, y.output  and  wants  to  include  no
       other information than the short statistics summary in y.output:
              hyacc -dD12 arith.y


       Here -D12 will suppress the states list.


       The user wants y.tab.c and y.tab.h, use optimization 1) only, and wants
       a default y.output:
              hyacc -d -O1 -v arith.y
              or
              hyacc -dO1v arith.y


       The user wants to parse the grammar and check y.output for information,
       and  doesn't need a compiler. While use all the optimizations, he wants
       to keep those unit productions with semantic actions:
              hyacc -cCv arith.y


DIAGNOSITICS
       Self explanatory.


AUTHOR
       Xin Chen &lt;chenx@hawaii.edu&gt;
       Send bug report or comments to the above address.




                          Version 0.95: 15 March 2009                 HYACC(1)
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